How to set Sharepoint 2007 into Read Only State

Please note that this can be done only with Sharepoint 2007 SP2.And usually this activity is done before an upgrade or migration.

1) Browse to Application Management -> Site Collection quotas and locks

2) Choose the Site Collection to see what the status is

3) Set to read only and set a custom message for the user to view.

Result

Site collection becomes read only and does not give the user the option to add content. The actions menus are empty.